About 10-15 years ago I received a kitchen knife in a dusty box. The box was old, had hieroglyphs all over, and the knife looked like a typical Chinese garbage with thin flexible blade and a simple handle. Since I absolutely hate this kind of tools, on my first attempt using I was cutting through a bone. I did it deliberately to get rid of the garbage ASAP. This ripped away a large chunk of steel near the handle , and when I packed the knife into its box to throw away, I noticed that it was a Japanese knife.
To make the story short, I still use the knife, and it became a favorite one among my quite expensive kitchen knife collection. It's razor sharp, keeps the edge exceptionally well, and only needed a few touch ups over all this time. The butchered beyond any repair area remains as a reminder of my stupidity. Every time I pick the knife I feel like I intentionally harmed my best friend.
Last night I found and bought the same model (NOS), but my old friend will still stay with me to keep me ashamed of myself.